VM access to existing VLAN

I need to configure OpenStack, to be able to give VMs access to an existing external network which is VLAN tagged.

I have a standard installation of OpenStack Mitaka (using neutron with ovs), with one external network already configured which provides the floating IPs for the VMs.

On each node I have two physical interface configured: one (eth0) not tagged and usef for the PXE boot of new nodes and the other one (eth1) with VLAN tags 32 for storage network and 34 for management, 36 for Piblic and a range from 200-600 for the Private network (tenants).

I tried to follow different tutorials / instructions to achieve my goal, but none of these worked.

I've also looked here for similar questions but none contained a full example, or exactly this case.

So, first of all, is it possible to have the standard floating IP setup and also direct access to external VLANs (let's say vlan 970) from VMs ?
And if the answer is yes, how can I set it up? Does anyone have working example or tutorial up to date?

Following the instructions on the different tutorials I linked here above, I'm able to have access to the VLAN from the compute and controller nodes (eth1.970) but the bridging (br-vlan) to the VM part doesn't appear to work.
Furthermore, it seems to be a lot different for each OpenStack version, for example: do I need another L3 agent? Should the interface be tagged or the bridge? And what about a router, do I need an additional one?